It is known to use so-called “weld nuts” or “weld studs” as part of fastener systems in various assemblies. It is known to secure the weld nut, weld stud or other component in a fixed position for later engagement with the complementary component of the fastener system, when it is difficult to access the nut or other fastener component in the completed assembly. For example, it is known to use weld nuts in blind locations on automobile frames where components later secured to the frame are positioned in a laid on assembly where the nut is not visible but must anchor a component overlying the nut. Weld nuts are used also in installations in which the anchoring component is of insufficient thickness to be threaded for anchoring a fastener, such as a bolt, directly. Again, by way of example, automobile frames are of such construction wherein frame members may be tubular to provide sufficient frame strength but each side of the tube is relatively thin and insufficient for threading to anchor a bolt to be secured thereto.
In such installations, weld nuts have worked satisfactory, but are not without deficiencies. After the second component of the fastener system has been secured in the nut and the two parts of the assembly drawn together, the security of the weld holding the nut in place is often inconsequential as the two components are secured together. However, if it is desired to disassemble the assembly, since the nut often is not accessible, the security of the nut in its mounted location is important to allow the bolt to be loosened therefrom without the nut spinning together with the bolt. Further, when completing the assembly, it is necessary to tighten the bolt sufficiently and the nut must stay in fixed position to allow proper tightening without the nut spinning with the bolt.
It is known to provide the surface of the weld nut or weld stud which is to bear against the sheet metal or supporting material with a plurality of raised integral projections or nibs. The weld nut or stud can be secured to the supporting material by resistance welding, which causes the projections to flow and alloy with the supporting material. If the weld is not secure, or if the fastening system is subjected to excessive torque or other forces, the weld zones can break loose, thus allowing the weld nut or stud to spin when the complementary fastener portion is connected thereto or disconnected therefrom.
It can happen that the thread of the complementary fastener component or the thread on the weld nut or weld stud itself can be malformed or damaged during handling or installation. This then has the effect of increasing the torque required during installation or disassembly. Application of increased torque on the welded attachment can cause the weld to fail, freeing the weld nut or weld stud from the installed position. Since the weld nut or weld stud is used specifically because it will be inaccessible in the completed assembly, if the weld fails and the weld nut or weld stud is freed, significant difficulties can result.
Accordingly, what is needed in the art is a fastener system utilizing a weld nut or weld stud which is more resistant to the application of high torque on the welded joint.